Spike positioning system

ABSTRACT

A spike positioning system includes an electro-optical device for locating spike receiving holes. The locating device is mounted on a spike positioning mechanism that is in turn mounted for movement by hydraulic cylinders. In use, the electro-optical device controls a servo system which operates the hydraulic cylinders. The cylinders in turn move the locating device and the spike positioning mechanism into alignment with a spike receiving hole.

[ Aug. 21, 1973 United States Patent [19] Bryan, Jr.

8/1949 Bayless 250/234 4/1970 104/12 Primary Examiner-Gerald M. Forlenza Assistant Examiner-Richard A. Bertsch Attorney-Richards, Harris & Hubbard [22] Filed:

[57] ABSTRACT A spike positioning system includes an electro-optical Related US. Application Data [63] Continuation-impart of Ser. No. 839,142, July 2,

1969, abandoned.

device for locating spike receiving holes. The locating device is mounted on a spike positioning mechanism that is in turn mounted for movement by hydraulic cylinders. In use, the electro-optical device controls a servo system which operates the hydraulic cylinders. The cylinders in turn move the locating device and the spike positioning mechanism into alignment with a spike receiving hole.

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[56] References Cited UNITED STATES PATENTS 3,405,649 10/1968 Foxx et 104/17 14 Claims, 6 Drawing Figures Patented Aug. 21, 1973 3,753,405

3 Shae ts-Sheet 1 u 1w JUL {I Iii 26 5 F IG. 2 38 JOHN F. BRYAN, JR.

ATTORNEY Patented Aug. 21, 1973 3,753,405

3 Sheets-Sheet 2 LOGIC HOLE SERVO AMPL'F'ER CIRCUIT ggL'P AMPLIFIER 62 62 I j [I 66 i SERVO 60 T MOTOR F IG. 3 5 62 58 LOGIC CENTERING Q AMPL'F'ER CIRCUIT CIRCUIT FLOW METER SERVO 8/ MOTOR FIG. 4 32 INVENTOR JOHN F. BRYAN, JR.

ATT'ORNEY Patented Aug. 21, 1973 3,753,405

3 Sheets-Sheet 3 sTART OF PULSE 9/2 HOLE LOCATION AMPLIFIER LOGIC 7 CIRCUIT PULSE PULSE DURATION COUNT I04 64 l FLOW CONTROL I02 66 ZH KEFTER J- SERVO 60 T MOTOR r T T INVENTOR: 6 JOHN F BRYAN, JR.

ATTORNEYS SPIKE POSITIONING SYSTEM REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of the earlier filed co-pending application of John F. Bryan, Jr., Ser. No. 839,l42, Filed July 2, 1969, now abandoned.

BACKGROUND OF THE INVENTION The rails of railroad and similar trackways are traditionally positioned on metal tie plates that are in turn positioned on wooden ties. The rails are secured to the ties by large metal spikes which are driven into the ties through holes formed in the tie plates. The use of the holes in the tie plates to guide the insertion of the spikes into the ties assures proper positioning of the spikes relative to the rails.

In the past, railroad spikes have been driven into ties either by means of sledge hammers or by means of power driven spike inserting devices. I-Ieretofore, however, the insertion of railraod spikes has been semiautomatic at best because no system had been provided for automatically aligning a power driven spike inserting device. That is, it has not previously been possible to automatically align a spike to be driven with a spike receiving hole in a tie plate so that the spike could be automatically driven into a tie by a power driven spike inserting device.

This invention relates to a system for automatically aligning a spike positioning mechanism with a spike receiving hole. The system includes an electro-optical spike receiving hole locating device and a servo system for guiding the positioning of a spike receiving mechanism in accordance with the output of the electrooptical device. Use of the system renders the insertion of railroad spikes fully automatic.

SUMMARY OF THE INVENTION In the preferred embodiment, this invention comprises a spike positioning system including a spike positioning mechanism and an electro-optical system for locating spike receiving holes. Preferably, the system includes a servo system responsive to the electrooptical system for moving the positioning mechanism into alignment with a spike receiving hole.

DESCRIPTION OF THE DRAWINGS A more complete understanding of the invention may be had by referring to the following detailed description when taken in conjunction with the drawings, wherein:

FIG. 1 is a side view of a spike positioning system employing the invention in which certain parts have been broken away more clearly to illustrate certain features of the invention;

FIG. 2 is a rear view of the device shown in FIG. 1;

FIG. 3 is a schematic illustration of a servo system employed in conjunction with the device illustrated in FIGS. I and 2;

FIG. 4 is a schematic illustration of an alternative embodiment of the system illustrated in FIG. 3;

FIG. 5 is a schematic illustration of another embodiment of the system illustrated in FIG. 3; and

FIG. 6 is a graph illustrating the operation of the system shown in FIG. 5.

DETAILED DESCRIPTION Referring now to the Drawings and particularly to FIG. 1 thereof, there is shown a rail 10 of the type typically employed in constructing railroads and similar trackways. The rail 10 is mounted on a metal tie plate 12 which is in turn mounted on a wooden rail 14. The tie plate 12 has a plurality of spike receiving holes 16 formed through it.

The rail 10 is secured to the tie 14 by large metal spikes that are driven into the tie 14 through the holes 16 in the tie plate 12. Consequently, during the construction of a trackway it is necessary to align each spike with a spike receiving hole before the spike can be driven into the tie. This invention relates to a system for automatically aligning spikes with spike receiving holes.

Referring now to FIG. 2, a spike positioning and inserting mechanism 18 is shown. The mechanism includes a pair of side plates 20 which are secured to a vehicle (not shown) similar to the small, motor driven vehicles typically employed in railroad maintenance and repair operations. The vehicle is operated to transport the spike positioning and inserting mechanism 18 to a site at which spikes are to be inserted. At the site, a mechanism on the vehicle (not shown) aligns the spike positioning and inserting mechanism 18 with a spike receiving hole in a direction extending transversely of the rails. Thereafter, the spike positioning and inserting mechanism 18 operates automatically to precisely align a spike with the spike receiving hole 16 in a direction extending longitudinally of the rails, whereupon the spike is driven through the hole into a tie 14.

The spike positioning and inserting mechanism 18 further includes a pair of piston rods 22 and 24, both of which extend between the side plates 20. The piston rods 22 and 24 are mounted in a pair of retaining members 26 which are in turn secured to the side plates 20 by a plurality of bolts 28. A pair of hydraulic cylinders 32 and 34 are mounted on the piston rods 22 and 24, respectively. Each of the cylinders 32 and 34 houses a piston (not shown) which is secured to its respective piston rod. In use, the cylinders 32 and 34 are moved back and forth along the piston rods 22 and 24 by supplying hydraulic fluid to and removing hydraulic fluid from their opposite ends.

The hydraulic cylinders 32 and 34 support a spike inserting hydraulic cylinder 36 and a spike positioning guideway 38. The cylinder 36 is of standard construction and operates to move a piston rod 40 upwardly and downwardly relative to the spike positioning and inserting mechanism 18. As is most clearly shown in FIG. 1, the piston rod 40 is normally enclosed in a guide sleeve 42 which extends downwardly from the hydraulic cylinder 36.

The spike positioning guideway 38 extends first parallel to and then beneath the hydraulic cylinder 36. Spikes are inserted into the upper portion of the guideway 38 either manually or by an automatic mechanism and fall through the guideway under the action of gravity. The lower portion of the guideway 38 is positioned directly beneath the piston rod 40 of the cylinder 36 and includes a pair of spike positioning springs 44 and a pair of spring loaded spike-retaining rollers 46-..As a spike falls through the guideway 38 it is brought into alignment with the piston rod 40 of the cylinder 36 by the springs 44 which operate to restrict the main portion of the spike to movement through the rear of the guideway 38. The rollers 46 engage the spike as it reaches the bottom of the guideway 38 and prevent it from falling out of the guideway 38 until it is driven therefrom by the operation of the cylinder 36.

In use, the hydraulic cylinders 32 and 34 are operated to position the guideway 38 in direct alignment with a spike receiving hole in a tie plate. Thereafter, the cylinder 36 is operated to drive a spike from the guideway 38 through the spike receiving hole 16 and into a tie.

It might at first appear that the use of the cylinders 32 and 34 is unnecessary since the guideway 38 could be aligned with a spike receiving hole by simply manipulating the vehicle upon which the spike positioning and inserting mechanism 18 is supported. However, in actual practice, four spike positioning and inserting mechanisms 18 are mounted on the vehicle, one on each side of each rail of the trackway. Often a particular tie may be positioned at a skewed angle relative to the longitudinal axis of the trackway. Also, the two tie plates that are supported on a particular tie are often slightly misaligned relative to each other. Thus, if all four of the positioning and inserting mechanisms on a vehicle were rigidly mounted, it would be frequently impossible to bring them all into alignment with four spike receiving holes at the same time. To this end, the spike positioning and inserting mechanism 18 is equipped with an automatic system for aligning the guideway 38 with a spike receiving hole.

As is most clearly shown in FIG. 1, the aligning system of the positioning and inserting mechanism 18 includes a spike receiving hole locating device 48 which is secured to and moved with the guideway 38. The hole locating device 48 may be a vidicon, an image or thicon, or any similar photoconductive image resolving device. Alternatively, the hole locating device 48 may be comprised of a laser or other source of intense radiation and a photocell or other radiation sensitive device. In either event, the hole locating device 48 serves to operate a servo system which in turn controls the operation of the cylinders 32 and 34 to bring the hole locating device 48, and therefore the guideway 38 to which it is attached, into alignment with a spike receiving hole. t

The operation of the electro-optical spike receiving hole locating device 48 to control the operation of the cylinders 32 and 34 in positioning the guideway 38 can be best understood by referring to FIGS. 3 and 4. Referring first to FIG. 3, a photoconductive image resolving device type hole locating device 48 is coupled through an amplifier 50 to a logic circuit 52. The logic circuit 52 produces an output whenever a spike receiving hole is positioned anywhere within the range of the photoconductive image resolving device. The logic circuit 52 is connected to a hole locating circuit 54. Whenever the logic circuit 52 produces an output, the hole location circuit 54 produces an output proportional to the amount of misalignment between the spike receiving hole and the center of the photoconductive image resolving device. This output is either positive or negative depending on the direction of misalignment. The output of the hole location circuit 54 is directed through a servo amplifier $6 to a servo motor 58. The servo motor 58 is in turn mechanically coupled to a three position, four way valve 60.

The valve 60 operates to control the flow of hydraulic fluid between four ports 62. Two of the ports 62 are coupled to a hydraulic fluid supply line 64 and to a hydraulic fluid return line 66, respectively. The remaining ports 62 are coupled to a pair of lines 68 and 70 which extend to the opposite ends of the cylinders 32 and 34, respectively.

In use, the servo motor 58 operates under control of the circuit 54 to control the position of the valve 60 relative to the ports 62. The valve 60 in turn couples the lines 64 and 66 to the appropriate ends of the cylinders 34 and 32 to cause movement of the cylinders in a centering direction. This action continues until the circuit 54 determines that the spike receiving hole locating device 48 is positioned in alignment with the spike receiving hole 16. When this occurs, the circuit 54 actuates the valve 60 through the servoamplifier 56 and the servo motor 58 to discontinue movement of the hydraulic cylinders 32 and 34. Since the spike receiving hole locating device 48 is coupled directly to the guideway 38, this positions the guideway 38 in alignment with the spike receiving hole.

Referring now to FIG. 4, a laser type electrooptical spike receiving hole locating device 48 and a second servo system are illustrated. The device 48 includes a laser 72 which produces ahigh energy output. The reflection of the output of the laser 72 is directed through a lens 74 to a photocell 76. The output of the photocell 76 is directed through an amplifier 78 to a logic circuit 80.

The logic circuit 80 is coupled to a centering circuit 82 which cooperates with the logic circuit 80 to control the operation of a servo motor 84. In addition to receiving an input from the amplifier 78, the logic circuit 80 receives an input from a flow meter 86 positioned in the hydraulic fluid supply line 64.

In use, the logic circuit 80is programmed to operate the valve 60 through the servo motor 84in such a way that the cylinders 32 and 34 initially move in a predetermined direction. During this action, the electrooptical spike receiving hole locating device 48 scans for a hole having the size of a spike receiving hole. Whenever the logic circuit 80 determines that the device 48 has traveled over such a-hole, it actuates the centering circuit 82. The circuit 82 in turn causes the servo motor 84 to reverse the travel of the cylinders 32 and 34. During this action, the flow meter 86 produces an output indicative of the distance traveled in the reverse direction.

When the logic circuit 80 determines that the cylinders 32 and 34 have traveled exactly half the width of a spike receiving hole 16 in the reverse direction, it discontinues the operation of both the centering circuit 82 and the servo motor 84. This action stops the movement of the cylinders 32 and 34. At this time, the spike receiving hole locating device 48 is positioned exactly in the center of the spike receiving hole 16. Since the guideway 38 is coupled directly to the device 48, the guideway 38 is therefore positioned in alignment with the spike receiving hole 16.

Referring now to FIG. 5, a third servo system is shown. The third servo system is actuated by a spike receiving hole locating device 48 comprising a vidicon, an image orthicon, or the like. The output of the spike receiving hole locating device 48 is coupled to an amplifier 90, and the output of the amplifier 90 is coupled to a hole locating logic circuit 92 through a pulse duration circuit 94 and a pulse count circuit 96 and through a start of pulse detection circuit 98. The hole location logic circuit 92 functions to produce an output indicative of the direction of misalignment of the spike receiving hole locating device 48 relative to a spike receiving hole. This output is coupled to a servo motor 100 through a servo amplifier 102. The servo motor 100 in turn controls the positioning of the three position, four way valve 60 to actuate the hydraulic cylinders 32 and 34. By this means, the spike receiving hole locating device 48, and therefore the guideway 38, are moved into alignment with the spike receiving hole.

The operation of the third servo system shown in FIG. 5 will be better understood by referring to FIG. 6 which comprises a trace of the output of the amplifier 90. Each vertical subdivision of FIG. 6 comprises one horizontal sweep of the spike receiving hole locating device 48. Any spike receiving hole lying within the sweep of the spike receiving hole locating device 48 appears as a square wave in the trace. The time T, is the time from the initiation of the sweep to the start of any particular pulse, and is therefore indicative of the direction of misalignment of the spike receiving hole locating device 48 from a spike receiving hole. The time period T is the duration of a particular pulse and is therefore indicative of the width of a spike receiving hole that is detected by the spike receiving hole locating device 48.

In the operation of the servo system shown in FIG. 5, the output of the amplifier 90 is sampled by the pulse duration circuit 94. Each pulse is monitored by the circuit 94 to determine whether the period T is equal in duration to a predetermined duration corresponding to a spike receiving hole. If this test is passed, the number of horizontal sweeps of the spike receiving hole locating device 48 in which the pulse occurs is counted by the pulse count circuit 96. The number of horizontal sweeps in whch the pulse occurs is indicative of the length of a spike receiving hole. Thus, if the count reached by the circuit 96 corresponds to a predetermined count corresponding to a spike receiving hole, it is known that a hole corresponding in length and width to a spike receiving hole has been located by the spike receiving hole locating device 48.

Whenever a spike receiving hole is identified by the pulse duration circuit 94 and the pulse count circuit 96, the hole location logic circuit 92 is actuated. The hole location logic circuit 92 is responsive to the time period T, as determined by the start of pulse detection circuit 98 to determine the direction of misalignment of the spike receiving hole locating device 48 from the spike receiving hole. That is, the output of the hole location logic circuit 92 is either positive or negative or nil depending on the positioning of the spike receiving hole locating device 48 to the left, or to the right, or in alignment with the spike receiving hole. The output of the hole location logic circuit 92 is amplified by the servo amplifier 102 whereupon the servo motor 100 positions either the left hand side, or the right hand side, or the center of the three position, four way valve 60 in alignment with the ports 62. By this means the hydraulic cylinders 32 and 34 are actuated to align the spike receiving hole locating device 48 with the spike receiving hole.

Those skilled in the art will realize that the servo system shown in FIG. 5 is capable of numerous modes of operation. For example, the rate of hydraulic flow through the lines 64 and 66 may be controlled at such a low rate that there is no possibility of "overshoot" of the hydraulic cylinders 32 and 34 as the hole locating device 48 comes into alignment with a spike receiving hole. In another mode, the cylinders 32 and 34 are caused to traverse very rapidly until the hole location logic circuit 92 notes that the spike receiving hole 10- cating device 48 is within a predetermined range of the spike receiving hole. At that time, the hole location logic circuit 92 actuates a flow control device 104, whereby the rate of flow of hydraulic fluid through the lines 64 and 66 is substantially reduced. That is, the rate of traverse of the cylinders 32 and 34 is reduced to the point that there is no possibility of overshoot when the spike receiving hole locating device 48 comes into alignment with the spike receiving hole. In accordance with still another mode of operation, the spike receiving hole locating device 48 is initially positioned to a particular side of a spike receiving hole, for example, the left side. In such a case, the rate flow of hydraulic fluid to the hydraulic cylinders 32 and 34 during leftward movement is very high, so that some overshoot is virtually certain. As soon as the hole location logic circuit 92 notes that the spike receiving hole locating device is positioned to the right of a spike receiving hole, the flow control device 104 is actuated to materially reduce the rate of hydraulic fluid flow to the cylinders 32 and 34. By this means the rate of return movement of the cylinders 32 and 34 is reduced to such a low level that no overshoot occurs. Other modes of operation of a servo system of the type shown in FIG. 5 will readily suggest themselves to those skilled in the art.

It should be understood that the servo systems illustrated in FIGS. 3, 4, and 5 are exemplary only in that mamy other types of servo systems can be employed in the practice of the invention. It should be further understood that whereas the embodiment of the invention illustrated in the Drawings operates to align a spike positioning mechanism in a direction extending parallel to the track, the invention can be employed to provide alignment in any direction and in two directions at once.

In the use of the invention, the vehicle which supports the side plates 20 is operated to roughly position the spike positioning and inserting mechanism 18 at a spike insertion location. A spike is then inserted into the guideway 38 whereupon it falls through the guideway into position beneath the piston of the hydraulic cylinder 36. During this action the springs 44 guide the spike into proper alignment with the piston 40 and the spring loaded rollers 46 restrain the spike from falling out of the guideway 38.

Before the cylinder 36 is actuated to insert the spike, the spike receiving hole locating device 48 is operated to precisely align the guideway 38 with a spike receiving hole. The device 48 operates through a servo system to actuate the cylinders 32 and 34 to move the guideway 38 into alignment with the spike receiving hole. As soon as the guideway 38 is aligned. the cylinder 36 is actuated to drive the spike through the rollers 36 and through the spike receiving hole into a tie, whereupon the spike secures a rail to the tie.

Although specific embodiments of the invention are illustrated in the Drawings and described herein, it will be understood that the invention is not limited to the embodiments disclosed but is capable of rearrangement, modification, and substitution of parts and elements without departing from the spirit of the invention.

What is claimed is:

l. A spike positioning system comprising:

a spike positioning mechanism;

a frame for supporting the spike positioning mechanism at a spike insertion location;

means for moving the spike positioning mechanism relative to the frame;

a photoconductive image resolving device secured to the spike positioning mechanism for movement therewith to scan the surface of a tie plate;

logic means for identifying an image detected by the photoconductive image resolving device as a spike receiving hole;

servo means responsive to the detection of a spike receiving hole by the photoconductive image resolving device for actuating the moving means to center the spike positioning mechanism and the photoconductive image resolving device on the spike receiving hole; and

means for thereafter driving a spike from the spike positioning mechanism and into the spike receiving hole.

2. The spike positioning system according to claim 1 wherein the spike positioning mechanism moving means comprises a pair of hydraulic cylinders for supporting the spike positioning mechanism on the frame and for moving the spike positioning mechanism relative to the frame under the control of the servo means.

3. The spike positioning system according to claim 1 wherein the actuating means includes circuitry coupled to the output of the photoconductive image resolving device for generating an output proportional to the distance between a spike receiving hole and the spike positioning mechanism.

4. The spike positioning system according to claim 1 wherein the actuating means includes circuitry coupled to the output of the photoconductive image resolving device for generating an output indicative of the direction of displacement between a spike receiving hole and the spike positioning mechanism.

5. The spike positioning system according to claim 1 wherein the spike positioning mechanism comprises means for orienting the spike in an insertion orientation, and wherein the spike driving means comprises a hydraulic cylinder for actuation after the spike positioning mechanism is aligned with the spike receiving hole to drive the spike into the spike receiving hole.

6. A spike positioning system comprising:

means for positioning a spike in an insertion orientation;

means for moving the spike positioning means along a line extending longitudinally of a rail and above a tie plate having a spike receiving hole formed therein;

a photoconductive image resolving device mounted for movement with the spike positioning means and oriented to scan along the line and hence across the tie plate;

logic means actuated by the photoconductive image resolving device for determining the scanning thereby of a spike receiving hole;

circuitry coupled to the output of the photoconductive image resolving device for generating an output indicative of misalignment between a spike receiving hole scanned by the photoconductive image resolving device and the spike positioning means; and

servo means responsive to the circuitry for actuating the moving means to align the spike positioning means with the spike receiving hole.

7. The spike positioning system according to claim 6 wherein the spike positioning moving means comprises a frame for supporting the spike positioning means at a spike insertion location and at least one hydraulic cylinder for moving the spike positioning means relative to the frame under the control of the servo means' 8. The spike positioning system according to claim 6 wherein the circuitry coupled to the output of the photoconductive image resolving device comprises a logic circuit for generating an output whenever a spike receiving hole is scanned by the photoconductive image resolving device and a hole location circuit for generating an output indicative of the direction of displacement between a spike receiving hole and the spike positioning means.

9. The spike positioning system according to claim 8 wherein the circuitry coupled to the output of the photoconductive image resolving device is further characterized by means for generating an output proportional to the distance between a spike receiving hole and the spike positioning means.

10. The spike positioning system according to claim 6 further including means operable after the spike positioning means has been aligned with the spike receiving hole for driving the spikeinto the spike receiving hole.

11. A spike positioning system comprising:

means for positioning a spike in an insertion orientation;

a frame for supporting the spike positioning means at a spike insertion location;

at least one hydraulic cylinder connected between the frame and the spike positioning means for moving the spike positioning means relative to the frame and along a line extending parallel to a rail and above the surface of a tie plate supporting the rail;

a photoconductive image resolving device secured to the spike positioning means for movement therewith along the line and oriented to scan along the line and across the upper surface of the tie plate;

logic means for identifying a portion of the scanned area as a spike receiving hole in the tie plate;

servo means coupled to the output of the photoconductive image resolving device for actuating the hydraulic cylinder to align the spike positioning means with a spike receiving hole scanned by the photoconductive image resolving device; and

a hydraulic cylinder for driving the spike out of the spike positioning means and into the spike receiving hole.

12. The spike positioning system according to claim 11 further characterized by a pair of hydraulic cylinders each for supporting the spike positioning means on the frame and each responsive to the servo means for moving the spike positioning means relative to the frame and along the line.

13. The spike positioning system according to claim 11 wherein the servo means includes circuitry for generating an output proportional to the distance between a spike receiving hole scanned by the vidicon tube and the spike positioning means.

14. The spike positioning system according to claim 13 wherein the servo means further includes valving means for controlling the flow of hydraulic fluid to the hydraulic cylinders and thereby controlling the operation of the cylinders to move the spike positioning means relative to the frame.

t W W i 

1. A spike positioning system comprising: a spike positioning mechanism; a frame for supporting the spike positioning mechanism at a spike insertion location; means for moving the spike positioning mechanism relative to the frame; a photoconductive image resolving device secured to the spike positioning mechanism for movement therewith to scan the surface of a tie plate; logic means for identifying an image detected by the photoconductive image resolving device as a spike receiving hole; servo means responsive to the detection of a spike receiving hole by the photoconductive image resolving device for actuating the moving means to center the spike positioning mechanism and the photoconductive image resolving device on the spike receiving hole; and means for thereafter driving a spike from the spike positioning mechanism and into the spike receiving hole.
 2. The spike positioning system according to claim 1 wherein the spike positioning mechanism moving means comprises a pair of hydraulic cylinders for supporting the spike positioning mechanism on the frame and for moving the spike positioning mechanism relative to the frame under the control of the servo means.
 3. The spike positioning system according to claim 1 wherein the actuating means includes circuitry coupled to the output of the photoconductive image resolving device for generating an output proportional to the distance between a spike receiving hole and the spike positioning mechanism.
 4. The spike positioning system according to claim 1 wherein the actuating means includes circuitry coupled to the output of the photoconductive image resolving device for generating an output indicative of the direction of displacement between a spike receiving hole and the spike positioning mechanism.
 5. The spike positioning system according to claim 1 wherein the spike positioning mechanism comprises means for orienting the spike in an insertion orientation, and wherein the spike driving means comprises a hydraulic cylinder for actuation after the spike positioning mechanism is aligned with the spike receiving hole to drive the spike into the spike receiving hole.
 6. A spike positioning system comprising: means for positioning a spike in an insertion orientation; means for moving the spike positioning means along a line extending longitudinally of a rail and above a tie plate having a spike receiving hole formed thereiN; a photoconductive image resolving device mounted for movement with the spike positioning means and oriented to scan along the line and hence across the tie plate; logic means actuated by the photoconductive image resolving device for determining the scanning thereby of a spike receiving hole; circuitry coupled to the output of the photoconductive image resolving device for generating an output indicative of misalignment between a spike receiving hole scanned by the photoconductive image resolving device and the spike positioning means; and servo means responsive to the circuitry for actuating the moving means to align the spike positioning means with the spike receiving hole.
 7. The spike positioning system according to claim 6 wherein the spike positioning moving means comprises a frame for supporting the spike positioning means at a spike insertion location and at least one hydraulic cylinder for moving the spike positioning means relative to the frame under the control of the servo means.
 8. The spike positioning system according to claim 6 wherein the circuitry coupled to the output of the photoconductive image resolving device comprises a logic circuit for generating an output whenever a spike receiving hole is scanned by the photoconductive image resolving device and a hole location circuit for generating an output indicative of the direction of displacement between a spike receiving hole and the spike positioning means.
 9. The spike positioning system according to claim 8 wherein the circuitry coupled to the output of the photoconductive image resolving device is further characterized by means for generating an output proportional to the distance between a spike receiving hole and the spike positioning means.
 10. The spike positioning system according to claim 6 further including means operable after the spike positioning means has been aligned with the spike receiving hole for driving the spike into the spike receiving hole.
 11. A spike positioning system comprising: means for positioning a spike in an insertion orientation; a frame for supporting the spike positioning means at a spike insertion location; at least one hydraulic cylinder connected between the frame and the spike positioning means for moving the spike positioning means relative to the frame and along a line extending parallel to a rail and above the surface of a tie plate supporting the rail; a photoconductive image resolving device secured to the spike positioning means for movement therewith along the line and oriented to scan along the line and across the upper surface of the tie plate; logic means for identifying a portion of the scanned area as a spike receiving hole in the tie plate; servo means coupled to the output of the photoconductive image resolving device for actuating the hydraulic cylinder to align the spike positioning means with a spike receiving hole scanned by the photoconductive image resolving device; and a hydraulic cylinder for driving the spike out of the spike positioning means and into the spike receiving hole.
 12. The spike positioning system according to claim 11 further characterized by a pair of hydraulic cylinders each for supporting the spike positioning means on the frame and each responsive to the servo means for moving the spike positioning means relative to the frame and along the line.
 13. The spike positioning system according to claim 11 wherein the servo means includes circuitry for generating an output proportional to the distance between a spike receiving hole scanned by the vidicon tube and the spike positioning means.
 14. The spike positioning system according to claim 13 wherein the servo means further includes valving means for controlling the flow of hydraulic fluid to the hydraulic cylinders and thereby controlling the operation of the cylinders to move the spike positioning means relative to the frame. 